1. Field of the Invention
The present invention relates to a compound-eye imaging device, and more particularly to a compound-eye imaging device having a function to detect eye positions of a person from images imaged thereby, the detected eye positions being usable to extract a face area from the images to perform personal identification based on the extracted face area.
2. Description of the Related Art
Imaging devices are known which have a function to recognize a face area contained in an image to perform personal identification. In the field of this kind of devices, Japanese Laid-open Patent Publication 2004-206688 discloses an imaging device to image by intentionally producing a so-called “red-eye” phenomenon, in which eyes of an imaged person are reproduced in red so as to accurately extract a face area. The imaging device. detects the face area based on the red-eye portions in the thus imaged image.
On the other hand, Japanese Laid-open Patent Publication 2003-30647 discloses an imaging device capable of flash imaging. In order to prevent a red-eye phenomenon, the imaging device uses both an image obtained by imaging with flash and an image obtained by imaging without flash so as to detect red-eye areas. This imaging device then electronically corrects the color of the thus detected red-eye areas to normal eye-color.
However, these known imaging devices have problems. In the imaging device disclosed in the above-described Japanese Laid-open Patent Publication 2004-206688, it is required that the red-eye portions in an image be accurately detected so as to accurately extract the face area. The detection of the red-eye portions is described therein as being performed by determining the size and shape of colored areas over the entire area of the image. In order to accurately detect red circular-shaped areas corresponding to the eyes (pupils), this imaging device requires performing a complex process that makes it possible to recognize and determine many patterns.
More specifically, a significantly complex process is required in order to discriminate and recognize red-eye areas of a person present in the image and red circular-shaped areas of e.g. a jewel present in the background of the image. This causes problems such as a significantly long process time until the detection of the red-eye areas, and a significantly high manufacturing cost of the imaging device itself due to the requirement of a significantly large software (program) to perform the complex process. Otherwise, if a simple process is used, there is a risk that the red-eye areas cannot be accurately detected, consequently making it unable to accurately extract a face area from the image, thus making the personal identification impossible.
On the other hand, the imaging device disclosed in the above-described Japanese Laid-open Patent Publication 2003-30647 uses both an image obtained by imaging with flash and an image obtained by imaging without flash so as to detect red-eye areas based on a comparison between both images. Accordingly, this imaging device makes it possible to accurately detect the red-eye areas with a relatively simple process. However, since it requires two steps of imaging with and without flash (two-step imaging), it has a disadvantage in that it takes a long time until the red-eye areas are detected.